PDBsum entry 3pys

Ribosome

PDB id: 3pys

Contents

Protein chains

234 a.a.

206 a.a.

208 a.a.

151 a.a.

101 a.a.

155 a.a.

138 a.a.

127 a.a.

98 a.a.

119 a.a.

124 a.a.

116 a.a.

60 a.a.

88 a.a.

83 a.a.

99 a.a.

70 a.a.

78 a.a.

99 a.a.

24 a.a.

DNA/RNA

Metals

_ZN ×2

References listed in PDB file

Key reference

• Title: Crystal structures of complexes containing domains from two viral internal ribosome entry site (ires) rnas bound to the 70s ribosome.
• Authors: J.Zhu, A.Korostelev, D.A.Costantino, J.P.Donohue, H.F.Noller, J.S.Kieft.
• Ref.: Proc Natl Acad Sci U S A, 2011, 108, 1839-1844.
• PubMed id: 21245352

Abstract

Internal ribosome entry site (IRES) RNAs are elements of viral or cellular mRNAs that bypass steps of canonical eukaryotic cap-dependent translation initiation. Understanding of the structural basis of IRES mechanisms is limited, partially due to a lack of high-resolution structures of IRES RNAs bound to their cellular targets. Prompted by the universal phylogenetic conservation of the ribosomal P site, we solved the crystal structures of proposed P site binding domains from two intergenic region IRES RNAs bound to bacterial 70S ribosomes. The structures show that these IRES domains nearly perfectly mimic a tRNA • mRNA interaction. However, there are clear differences in the global shape and position of this IRES domain in the intersubunit space compared to those of tRNA, supporting a mechanism for IRES action that invokes hybrid state mimicry to drive a noncanonical mode of translocation. These structures suggest how relatively small structured RNAs can manipulate complex biological machines.